Plastic packaging method



Jan. 2, 1968 c. N. KRACHT ET AL PLASTIC PACKAGING METHOD Original Filed June 7, 1962 l In ll fl Il Il I il Il Il l TORS . ,e1/:Hr

$502.75 6,' SMBs/vow f4 TTORNEY United States Patent O 3,360,899 PLASTIC PACKAGING METHOD Clyde N. Kracht, Darien, Conn., and George C. Stabenow, Hinsdale, Ill., assignors to Union Carbide Corporation, a corporation of New York Original application .lune 7, 1962, Ser. No. 200,753, now Patent No. 3,255,877, dated June 14, 1966. Divided and this application Get. 8, 1965, Ser. No. 510,419

4 Claims. (Cl. 53-30) This application is a division of application Ser. No. 200,753, filed June 7, 1962, and now Patent No. 3,255,- 877, issued June 14, 1966.

This invention relates to packaging and more particularly to the formation of packages in which the contents are wrapped tightly in a transparent film of plastic.

The invention provides a package consisting of a semirigid pallet of biaxially oriented cellular thermoplastic sheet material having the shape of the lower portion of the contents of such package for nesting and supporting such contents in a predetermined arrangement, and a transparent envelope of biaxially oriented transparent thermoplastic film surrounding and binding such contents and pallet together as a unit.

According to the invention there is provided a method of forming a package having a Wrapper of transparent protective film smoothly embracing the upper portion of the contents of such package, which comprises heat-preforming a pallet of biaxially oriented thermoplastic sheet material to correspond to the shape of the lower portion of such contents to provide a nest therefor, by molding such material with the aid of heat sufficient only to partially shrink such material. Such contents are nested in such pallet :and the pallet and so-nested contents are enclosed in an envelope of biaxially oriented thermoplastic film, so that such iihn surrounds both the pallet and contents in fitting relation. Finally the film and pallet are subjected to heat sufficient to shrink both of them tightly about such contents in firmly embracing and unitizing relationship.

The invention particularly provides for tightly wrapping into a transparent plastic overwrap, an elongated bundle of similar or diverse articles. Such articles are nested in a preformed support of heat-shrinkable cellular -plastic sheet. Such support and the so-nested articles are provided with an overwrap of heat-shrinkable thermoplastic film; and concurrent heat-shrinking of the support and overwrap are -accomplished to forma durable bundle of tightly interlocked items.

More particularly, the invention provides a stiff, durable multipack of a plurality of uniform or ununiform loose items, placed into an orderly, extensive arrangement. It has been used, for example, in making a rigid four-count pack of uniform cans of fruit juices into a one-long, two-wide and two-high arrangement.

The method may also be used to great advantage, to bundle, support and protect ununiform and/or fragile items, such las fingers or bunches (approximately two pounds) of bananas, thereby reducing or eliminating bruises and scarring of fruit removed from the stalk at the plantation and there packaged for shipment to the customer.

The reasons for using a multipack in some merchandising operations generally involves the extra convenience for the shopper including:

(l) Easy carrying of several units.

I(2) Greater variety-products in different flavors and sizes can be sampled and well-known favorites can help the introduction of brand new products.

(3) Simplified shopping--Multipacks are excellent means of combining different products that go together naturally, such as canned fruit and a pie mix.

M1ce

It is desirable to have multipacks of long, narrow cans, such as those used for concentrated fruit juices, arranged into a vertical stack. Such a vertical multipack of four cans is more readily racked on the retail store shelves to achieve the desired effective display of brand name.

Previous method of packaging multipacks in vertical arrangement were not entirely satisfactory. They used paperboard support pallets, die cut and folded to separate the chines (beads) of mating cans, and were curved partly Aabout the can bodies to support them. It was difficult to assemble and align cans on such folded paperboard pallets and maintain them in alignment during insertion into the overwrap film sleeve. Previous methods did not prevent misalignment of the cans in end-to-end arrangement after shrinking the sleeve overwrap about the can items and paperboard pallet, nor did they provide a rigid enough package to support a plurality of elongate items.

Such problems and diiculties are avoided by the present invention in which, for example, a preformed pallet of biaxially oriented cellular plastic such as polystyrene, polyurethane or polypropylene sheet, is preshaped in a partial shrinking operation (about 1/3 to 1/2 total shrink) to conform generally to the desired bundling arrangement of items. This provides the necessary strength and rigidity for a rigid, durable package when it is ultimately, concurrently shrunk about the product items in combination with a heat-shrinkable overwrap of biaxially oriented polypropylene film.

The preformed pallet is preferably made of cellular plastic sheeting, so that it can be partially heat-shrunk and compressed to a shape approximating that of the items constituting the contents, thereby permitting the items to be readily nested therein for easy insertion into the film wrapper. In the final heat-shrink operation, the film wrapper and pallet are concurrently shrunk and tightly drawn down about the items, thereby compressing, compacting and interlocking the cellular sheet pallet about protruding surfaces of the items to immobilize them, one to the other. The film overwrap binds the items and pallet together into :a durable multipack with a perimeter seal.

In the case of a multipack of loose fingers or a connected bunch or cluster of bananas, former packaging did not prevent shifting or bruising the fruit. A preformed pallet of biaxially oriented foamed polystyrene sheet, generally shaped to the number and configuration of bananas involved and made to interlock the unit fruit fingers, according to the invention, provides the necessary support for a strong, rigid package when concurrently heat-shrunk in combination with a heat-shrinkable overwrap of biaxially oriented polypropylene film.

The main object of the invention is to provide a method for making a multipack with a transparent overwrap film which results in a strong, rigid, durable unit package for a plurality of product items that are arranged into an elongate bundle. l

Another object is to provide an elongate package article that can be stacked vertically and have a surface that is transparent, to display the contents and to reveal the pallet. It is also desirable that the outer surface of the pallet can be used as ia printing surface for promotional advertising, etc.

Other objects are to advance the art by improving the packaging of such items so that they are protected, yet displayed with attractive effect.

The invention involves:

(l) Making a preformed pallet of shrinkable cellular plastic sheet which is only partially shrunk to a shape that cradles the product items to be packaged into the preferred arrangement.

(2) Placing such product items in such preformed pallet.

(3) Inserting the pallet and product items into a shrinkab-le film sleeve of appropriate circumference and length.

(4) Concurrently heat-shrinking the pallet and film sleeve tightly about the periphery of the preferred arrangement of the product items, to interlock them into a durable package.

In the drawing:

FIG. 1 is a perspective view of a package illustrating the invention;

FIG. 2 is a view in side elevation of such package; and

FIGS. 3 and 4 are enlarged fragmentary cross-sections of the package taken in the zones 3 and 4, respectively of FIG. 2.

As shown in such drawing, four cans of fruit juice concentrate or similar elongate items are vertically stacked (end-to-end) to obtain the desired commercial display value. A 6" X 10" sheet of .025r thick biaxially oriented cellular polystyrene of 14 pounds per cubic feet density, with a gloss surface, is preformed into a suitable pallet 12 by pressing it down about a half-section template of the desired can arrangement, and simultaneously heatshrinking it to approximately 25 to 33 percent of final shrink. The cellular sheet is thereby shaped into the pallet 12 about the end beads 14 and mating beads 16 of the can arrangement and into the open V-groove 1d between the curved surfaces of the can items.

The four can items 10, each 23716 diameter by 37s long, are nested into the preformed pallet 12 and the assembly is inserted into a l1" long sleeve 20, of 6" flat width seamless tubing made of .001" thick biaxially oriented polypropylene films. In the preferred method, a perimeter seal is made in the overwrap film by hot-wire sealing the ends of the film sleeve. However, if desired, the sleeve ends may be left open for the next step.

The assembly of pallet 12, cans 10 and the overwrap sleeve is then concurrently heat-shrunk with the bottom (preformed pallet side) up, in a heated air chamber, at a temperature of about 135 C., for about 11/2 minutes. The heated air concurrently shrinks the film overwrap 20 and pallet 12, drawing the pallet down tightly about the items, and compacting the cellular sheet at the corners and protruberences to form a rigid, durabley bundle.

Compacting of the cellular plastic pallet l2 about the can beads 14 and 16 is caused by the tension in the film overwrap 20 as it is heat-shrunk concurrently with the pallet. The compressible cellular plastic sheet of the pallet is compacted -by the film overwrap `about the corners and beads of the package, as at 22 and 24, to about less than one-third of its original thickness. Where the compressible sheet bridges the beads or corners, as at 2S and 26, it blends fromthe original thickness to the compacted thickness and thereby serves to immobilize and interlock the can items together.

The compressible pallet preform may be made of any cellular plastic material, such as .020 to .040 thick, smooth-surfacedsheets of foamed polystyrene, polypropylene or polyurethane, which is capable of being heati shrunk to less than about 85 percent of its original area and can be compacted by the pressure of a heat-shrunk overwrap film to a thickness not less than about percent of its original thickness. The overwrap film is preferably made of biaxially oriented polypropylene of about .001 thickness. However, any plastic film which has the acceptable clarity and may be heat-shrunk to less than percent of its original area, and is capable of providing a heat-seal strength of 5 to 10 pounds per inch length, would be satisfactory in combination with the abovedisclosed pallet to practice the method of this invention.

What is claimed is:

l. The method of forming a package having a wrapper of transparent, protective film smoothly embracing a portion of the contents of such package, which comprises heat-preforrning a pallet of biaxially oriented thermoplastic sheet material to correspond to the shape of the lower portion of such contents to provide a nest therefor, by molding such material with the aid of heat sufficient only to partially shrink such material, nesting such contents in such pallet, inserting the pallet and so-nested contents in a tubular section of biaxially oriented thermoplastic film, so that such film surrounds both the pallet and contents in fitting relation, and finally subjecting the film and pallet to heat sufiicient to shrink both of them tightly about such contents in firmly embracing relationship.

Z. The method as defined by claim 1, in which the package contents are a plurality of cans stacked side-byside, the pallet is composed of a 0.025 inch thick sheet of biaXially oriented cellular polystyrene of the order of 14 pounds per cubic foot density heat shrunk in preforming to 25 to 33 percent of final shrink, and the wrapper is composed of seamless tubing consisting of 0.001 inch thick biaxially oriented polypropylene film.

3. The method as defined by claim 1, in which the ends of tubing are also sealed together.

1i. Method of packaging product items which comprises making a preformed pallet of shrinkable cellular plastic sheet which is only partial-ly shrunk to a shape that cradles the product items to be packaged into the preferred arrangement; packing such product items in such preformed pallet, inserting the pallet and product items into a shrinkable film sleeve of appropriate circumference and length, and concurrently heat-shrinking the pallet and film sleeve tightly about the periphery of the preferred arrangement of the product items, to interlock them into a durable package.

leerer-fences Cited UNlTED STATES PATENTS 3,071,906 1/1963 Zebarth et al 53-184 XR 3,093,448 6/1963 Kirkpatrick et al. 53-30 3,187,477 6/1965 Dreyfus 53-30 3,190,050 6/1965 Kirkpatrick 53-30 GRANVILLE Y. CUSTER, IR., Primary Examiner'. 

1. THE METHOD OF FORMING A PACKAGE HAVING A WRAPPER OF TRANSPARENT, PROTECTIVE FILM SMOOTHLY EMBRACING A PORTION OF THE CONTENTS OF SUCH PACKAGE, WHICH COMPRISES HEAT-PREFORMING A PALLET OF BIAXIALLY ORIENTED THERMOPLASTIC SHEET MATERIAL TO CORRESPOND TO THE SHAPE OF THE LOWER PORTION OF SUCH CONTENTS TO PROVIDE A NEST THEREFOR, BY MOLDING SUCH MATERIAL WITH THE AID OF HEAT SUFFICIENT ONLY TO PARTIALLY SHRINK SUCH MATERIAL, NESTING SUCH CONTENTS IN SUCH PALLET, INSERTING THE PALLET AND SO-NESTED CONTENTS IN A TUBULAR SECTION OF BIAXIALLY ORIENTED THERMOPLASTIC FILM, SO THAT SUCH FILM SURROUNDS BOTH THE PALLET AND CONTENTS IN FITTING RELATION, AND FINALLY SUBJECTING THE FILM AND PALLET TO HEAT SUFFICIENT TO SHRINK BOTH OF THEM TIGHTLY ABOUT SUCH CONTENTS IN FIRMLY EMBRACING RELATIONSHIP. 